Method and apparatus for analyzing elastography of tissue using ultrasound waves

ABSTRACT

A method and apparatus for analyzing elastography of tissue using ultrasound waves, wherein elastography information of tissue in a region of interest (ROI) is analyzed by irradiating ultrasound waves for diagnosis towards the ROI to which a shear wave is induced from an ultrasound probe, receiving echo ultrasound waves, and acquiring three-dimensional (3D) ultrasound images with respect to the ROI.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/919,303, filed on Jun. 17, 2013, which claims the benefit of KoreanPatent Application No. 10-2012-0086937, filed on Aug. 8, 2012, in theKorean Intellectual Property Office, the disclosures of which areincorporated herein in their entirety by reference.

BACKGROUND 1. Field

One or more embodiments of the present disclosure relate to methods andapparatuses for analyzing elastography of tissue of a human or animalsubject using ultrasound waves.

2. Description of the Related Art

To diagnose a disease, establish a treatment plan, or evaluate atreatment progress using ultrasound images in medical institutions, amedical practitioner reads ultrasound images of a patient, which aredisplayed on a monitor, to observe states or sequential histologicalchanges of tumorous or cancerous tissue. However, since ultrasoundimages are read by a medical practitioner with the naked eye, the sameultrasound image may be analyzed differently depending on the angle ofview of the medical practitioner, thereby making the potential for ameasurement error large. In addition, occasionally, a medicalpractitioner incorrectly recognizes abnormal tissue, such as tumorous orcancerous tissue in ultrasound images as normal tissue, that is tissuewithout tumors or cancer.

However, recently, Computer-Aided Diagnosis (CAD) systems primarilydiscerning medical images, such as ultrasound images, Magnetic ResonanceImaging (MRI) images, and Computed Tomography (CT) images, andindicating the presence or absence of abnormal tissue, a location of theabnormal tissue, and the like to a medical practitioner have beendeveloped. The CAD systems, which detect abnormal tissue by processingthe presence or absence of abnormal tissue in a medical image, a size ofthe abnormal tissue, a location of the abnormal tissue, and the likeusing a computer system and provide a detection result to a medicalpractitioner to aid image diagnosis by the medical practitioner, may beused in combination with medical devices, such as an ultrasound device,an MRI device, and a CT device.

SUMMARY

Provided are methods and apparatuses for analyzing elastography oftissue in a subject using ultrasound waves.

Provided are computer-readable recording media storing acomputer-readable program for executing the methods.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

According to an aspect of the present disclosure, a method of analyzingelastography of tissue using ultrasound waves includes: irradiatingultrasound waves for diagnosis towards a region of interest (ROI) in asubject, to which a shear wave is induced, from an ultrasound probehaving a two-dimensional (2D) transducer array; acquiringthree-dimensional (3D) ultrasound images with respect to the ROI usingecho ultrasound waves of the ultrasound waves for diagnosis, which havebeen received by the ultrasound probe; measuring a displacement of theshear wave in the ROI from the acquired 3D ultrasound images; andanalyzing information about elastography of tissue in the ROI using themeasured displacement of the shear wave.

According to another aspect of the present disclosure, acomputer-readable recording medium storing a computer-readable programfor executing the method of analyzing elastography of tissue usingultrasound waves in a computer system is provided.

According to another aspect of the present disclosure, an apparatus foranalyzing elastography of tissue using ultrasound waves includes: anultrasound probe for irradiating ultrasound waves for diagnosis towardsa region of interest (ROI) in a subject, to which a shear wave isinduced, using a two-dimensional (2D) transducer array; an ultrasoundimage processor for acquiring three-dimensional (3D) ultrasound imageswith respect to the ROI using echo ultrasound waves of the ultrasoundwaves for diagnosis, which have been received by the ultrasound probe; adisplacement measuring unit for measuring a displacement of the shearwave in the ROI from the acquired 3D ultrasound images; and anelastography analyzing unit for analyzing information about elastographyof tissue in the ROI using the measured displacement of the shear wave.

According to another aspect of the present disclosure, a system toanalyze elastography of tissue using ultrasound waves is provided. Thesystem includes an ultrasound probe to irradiate a region of interest(ROI) in a subject with ultrasound waves thereby inducing a shear wavein the ROI and a processor. The processor includes an ultrasound imageprocessor to acquire three-dimensional (3D) ultrasound images of the ROIusing echo ultrasound waves provided by the ultrasound probe, whereinthe echo ultrasound waves are obtained from the ultrasound waves afterthe ultrasound waves are reflected from the ROI or regions around theROI, a displacement measuring unit to measure a displacement of theshear wave in the ROI based on the acquired 3D ultrasound images, and anelastography analyzing unit to analyze information about elastography oftissue in the ROI using the measured displacement of the shear wave.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee. These and/or other aspects will become apparentand more readily appreciated from the following description of theembodiments, taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a block diagram of an apparatus for analyzing elastography oftissue using ultrasound waves, according to an embodiment of the presentdisclosure;

FIG. 2A is a diagram for describing a shear wave according to anembodiment of the present disclosure;

FIG. 2B is an image showing that a shear wave is induced to a region ofinterest (ROI) according to an embodiment of the present disclosure;

FIG. 3A is a perspective view showing a case where ultrasound waves fordiagnosis are irradiated by a 3D volume acquisition method according toan embodiment of the present disclosure;

FIG. 3B is a perspective view showing a case where ultrasound waves fordiagnosis are irradiated by a 3D plane scan method according to anembodiment of the present disclosure;

FIG. 4A is an image showing a simulation result of a case where a shearmodulus is analyzed from 2D ultrasound images acquired using an existingultrasound probe having a 1D transducer array;

FIG. 4B is an image showing a simulation result of a case where a shearmodulus is analyzed from 3D ultrasound images acquired using anultrasound probe having a 2D transducer array according to an embodimentof the present disclosure; and

FIG. 5 is a flowchart illustrating a method of analyzing elastography oftissue using ultrasound waves, according to an embodiment of the presentdisclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of whichare illustrated in the accompanying drawings, wherein like referencenumerals refer to like elements throughout. In this regard, the presentembodiments may have different forms and should not be construed asbeing limited to the descriptions set forth herein. Accordingly, theembodiments are merely described below, by referring to the figures, toexplain aspects of the present description.

FIG. 1 is a block diagram of an apparatus 1 for analyzing elastographyof tissue using ultrasound waves, according to an embodiment of thepresent disclosure. Referring to FIG. 1, the apparatus 1 may include,for example, a processor 10 and an ultrasound probe 20. The processor 10may include, for example, an ultrasound image processor 110, adisplacement measuring unit 120, and an elastography analyzing unit 130.

Only hardware components associated with the current embodiment aredescribed in FIG. 1 to prevent features of the current embodiment frombeing obscured. However, it will be understood by one of ordinary skillin the art that the apparatus 1 may further include other general-usehardware components.

Recently, systems, such as Computer-Aided Diagnosis (CAD) systems,primarily discerning medical images, such as ultrasound images, MagneticResonance Imaging (MRI) images, and Computed Tomography (CT) images, andproviding the presence or absence of abnormal tissue, a location of theabnormal tissue, and the like to a medical practitioner have been used.The systems may detect abnormal tissue by processing the presence orabsence of abnormal tissue in a medical image, a size of the abnormaltissue, a location of the abnormal tissue, and the like using a computersystem and provide a detection result to a medical practitioner to aidimage diagnosis by the medical practitioner.

The apparatus 1 may be used in systems such as the CAD systems describedabove. Ultrasound elastography technology may be used to diagnose tissueby analyzing elastography of the tissue and discerning a stiffnessdifference between normal tissue and abnormal tissue. In particular, theapparatus 1 may be used to discern a state of tissue in the human body,or in animal tissue, such as whether abnormal tissue, such as cancer,exists or whether tissue has been completely treated when the tissue istreated using High Intensity Focused Ultrasound (HIFU) or the like, byanalyzing elastography of the tissue using ultrasound waves.

In general, it is known that abnormal tissue has a difference instiffness compared with normal tissue, and the abnormal tissue may bediscerned by analyzing this difference. Thus, abnormal tissue, such ascancerous tissue or tissue having a tumor, may have a higherelastography score than surrounding normal tissue. Thus, a shear modulusof the abnormal tissue is higher than that of the surrounding normaltissue. In addition, when tissue is treated by necrosing it usingultrasound waves for treatment, such as in HIFU, an elastography scoreof the tissue increases as necrosis of the tissue progresses. That is, astate change of tissue may be determined or monitored by an elastographyof the tissue. Thus, if elastography of the tissue is perceived usingultrasound waves, a medical practitioner may non-invasively monitor astate of the tissue without having to view the tissue in the human bodywith the naked eye.

The apparatus 1 may be configured as a system capable of aiding imagediagnosis by a medical practitioner in a medical institution and may beused to diagnose a disease, establish a treatment plan, and evaluate atreatment progress by providing a result of analyzing elastography oftissue using ultrasound waves. Alternatively, the apparatus 1 may beused to detect diseased tissue in a living animal or may be used toinspect animal tissue of a living or dead animal, such as to determinethe quality of animal meat for human consumption. A configuration andoperation of the apparatus 1 will now be described in more detail.

The ultrasound probe 20 induces a shear wave by radiating ultrasoundwaves upon a region of interest (ROI) 30 in the human body beforeelastography is analyzed. To quantitatively analyze the elastographyusing the ultrasound waves for diagnosis, Acoustic Radiation ForceImpulses (AFRIs) equivalent to the ultrasound waves for diagnosis needto be applied to the human or animal body in advance to cause adisplacement of tissue. That is, the AFRIs induce a shear wave to thetissue to cause the displacement of the tissue.

FIG. 2A is a diagram for describing a shear wave according to anembodiment of the present disclosure. Referring to FIG. 2A, when a forceof a point impulse is applied along a z-axis direction, a P wave that isa longitudinal wave, an S wave that is a transverse wave, and a PS wavethat is a coupling wave of the P wave and the S wave are generated. Theshear wave is a wave vibrating along a wave traveling direction andtraveling along a y-axis direction from a vibration source to which theforce is applied, i.e., the S wave.

It is described in the current embodiment for convenience of descriptionthat the ultrasound waves for diagnosis from the ultrasound probe 20 areused for the force of the point impulse for inducing the shear wave.However, the current embodiment is not limited thereto, and a treatmentultrasound device, such as an HIFU device, or an oscillator locatedoutside the apparatus 1 may also be used to induce the shear wave. Thatis, it will be understood by one of ordinary skill in the art that adevice for inducing the shear wave to the ROI 30 is not limited to anyone device and may include a variety of different devices.

FIG. 2B is an image showing a shear wave being induced in the ROI 30according to an embodiment of the present disclosure. Referring to FIG.2B, the ultrasound probe 20 induces the shear wave in the ROI 30 byradiating the ultrasound waves for diagnosis along a depth-axisdirection to form a focal point on the ROI 30 under the skin of thehuman body, thereby irradiating the ROI.

Referring back to FIG. 1, the ultrasound probe 20 radiate the ultrasoundwaves towards the ROI 30 thereby irradiating the ROI 30 to obtainultrasound images of the ROI 30 and regions around the ROI 30 after theshear wave is induced in the ROI 30.

The ultrasound probe 20 may radiate plane waves by beamforming theultrasound waves in a defocusing method. The plane waves are used in thedefocusing method is to allow the shear wave to be observed in a widerrange.

In more detail, the ultrasound probe 20 may use the defocusing method sothat a displacement of the shear wave is observed in a wider range thanwould be observed if a focusing method were used. In addition, by usingplane waves having a strength that is maintained relatively constanteven when the plane waves reach a location deep in the human body, adisplacement of the shear wave may be more correctly observed thanspherical waves having a strength that weakens as they reach a deeplocation.

The ultrasound probe 20 may include a 2D transducer array to acquire 3Dultrasound images at high speed, as described with reference to FIGS. 3Aand 3B.

FIG. 3A is a perspective view showing ultrasound waves being radiatedusing a 3D volume acquisition method according to an embodiment of thepresent disclosure. Referring to FIG. 3A, the ultrasound probe 20 mayirradiate the ROI 30 with the ultrasound waves using the 2D transducerarray to scan a 3D volume of the ROI 30 and regions around the ROI 30 atonce, that is, to scan the 3D volume simultaneously or within a veryshort period of time.

FIG. 3B is a perspective view showing a case where the ultrasound wavesare radiated using a 3D plane scan method according to an embodiment ofthe present disclosure. Referring to FIG. 3B, the ultrasound probe 20may irradiate the ROI 30 with the ultrasound waves using the 2Dtransducer array to scan the ROI 30 and regions around the ROI 30 on aplane basis and generate 3D volume data with respect to the ROI 30.

Referring back to FIG. 1, the ultrasound probe 20 receives echoultrasound waves. The echo ultrasound waves are the original ultrasoundwaves after being reflected from the ROI 30 and the regions around theROI 30. As described above, since the ultrasound probe 20 radiates theultrasound waves using either of the 2D transducer array in the 3Dvolume acquisition method or the 3D plane scan method, the ultrasoundprobe 20 may receive echo ultrasound waves including 3D informationabout the ROI 30 and the regions around the ROI 30.

In general, it is known that a wave speed of the shear wave is about 1m/s to about 10 m/s. Thus, to observe the shear wave with a resolutionof several mm, ultrasound images may need to be acquired in units ofthousands of frames per second. To acquire ultrasound images ofthousands of frames per second, the ultrasound waves for diagnosis needto be irradiated and received at a speed faster than the wave speed ofthe shear wave. In this case, since an existing 3D line scan method canscan only a single scan line at a time, ultrasound images of thousandsof frames per second cannot be acquired and it may be difficult tocorrectly measure the movement of the shear wave using the 3D line scanmethod. Thus, by instead using the methods shown in FIG. 3A or 3B, 3D,ultrasound images of thousands of frames per second may be acquiredusing the 2D transducer array, thereby correctly measuring the movementof the shear wave.

The ultrasound image processor 110 may acquire 3D ultrasound images ofthousands of frames per second by processing the echo ultrasound wavesreceived by the ultrasound probe 20. In other words, the ultrasoundimage processor 110 may acquire 3D ultrasound images of thousands offrames per second by beamforming the echo ultrasound waves received bythe ultrasound probe 20. Since a typical process of processingultrasound images by using echo ultrasound waves would be apparent toone of ordinary skill in the art, a detailed description thereof isomitted.

The displacement measuring unit 120 measures a displacement of the shearwave in the ROI 30 from the acquired 3D ultrasound images. Since the 3Dultrasound images are acquired by the ultrasound image processor 110 asdescribed above, the displacement of the shear wave that is measured bythe displacement measuring unit 120 corresponds to measured 3D movementof the shear wave. That is, the measured displacement of the shear wavehas displacement components corresponding to the x-, y-, and z-axes inan arbitrary 3D coordinate space.

Since a typical process of measuring a displacement of a shear wave byanalyzing movement of the shear wave, which is shown in ultrasoundimages of thousands of frames per second, would be apparent to one ofordinary skill in the art, a detailed description thereof has beenomitted.

The elastography analyzing unit 130 analyzes elastography information oftissue in the ROI 30 using the measured displacement of the shear wave.The elastography information analyzed in the current embodiment mayinclude a shear modulus.

The elastography analyzing unit 130 may calculate a shear modulus of thetissue in the ROI 30 using the displacement components corresponding to3D coordinate axes (x-, y-, and z-axes) that are included in themeasured displacement of the shear wave. In this case, the elastographyanalyzing unit 130 may calculate the shear modulus using a wave equationwith respect to the shear wave.

In more detail, the elastography analyzing unit 130 may calculate amoving speed of the shear wave using the displacement componentscorresponding to the 3D coordinate axes that are included in themeasured displacement of the shear wave.

$\begin{matrix}{\frac{\partial^{2}u}{\partial t^{2}} = {C_{S}^{2} \cdot \left( {\frac{\partial^{2}u}{\partial x^{2}} + \frac{\partial^{2}u}{\partial y^{2}} + \frac{\partial^{2}u}{\partial z^{2}}} \right)}} & (1)\end{matrix}$

In Equation 1, u denotes a displacement of a shear wave and C_(S)denotes a moving speed of the shear wave. Although the elastographyanalyzing unit 130 may calculate the moving speed C_(S) of the shearwave using Equation 1 in the current embodiment, the current embodimentis not limited thereto.

The elastography analyzing unit 130 may calculate a shear modulus of thetissue in the ROI 30 using the calculated moving speed C_(S) of theshear wave.

G=ρ×C _(S) ²  (2)

In Equation 2, G denotes a shear modulus, and p denotes density of amedium. Since the elastography analyzing unit 130 may calculate themoving speed C_(S) of the shear wave using Equation 1 as described aboveand p is an already known value, the elastography analyzing unit 130 maycalculate the shear modulus G using Equation 2. Although theelastography analyzing unit 130 calculates the shear modulus G usingEquation 2 in the current embodiment, the current embodiment is notlimited thereto.

If the elastography analyzing unit 130 analyzes the shear modulus G inunits of at least two frames in the 3D ultrasound images, theelastography analyzing unit 130 may calculate a final shear modulus G bycalculating a mean value of the calculated shear moduli G.

Alternatively, the elastography analyzing unit 130 may calculate theshear modulus G using Equation 3 below.

$\begin{matrix}{{\rho \frac{\partial^{2}u_{z}}{\partial t^{2}}} = {\left. {{G\left( {x,y,z} \right)}\left( {\frac{\partial^{2}u_{z}}{\partial x^{2}} + \frac{\partial^{2}u_{z}}{\partial y^{2}} + \frac{\partial^{2}u_{z}}{\partial z^{2}}} \right)}\Leftrightarrow{G\left( {x,y,z} \right)} \right. = \frac{\rho \frac{\partial^{2}u_{z}}{\partial t^{2}}}{\frac{\partial^{2}u_{z}}{\partial x^{2}} + \frac{\partial^{2}u_{z}}{\partial y^{2}} + \frac{\partial^{2}u_{z}}{\partial z^{2}}}}} & (3)\end{matrix}$

That is, the elastography analyzing unit 130 may calculate the shearmodulus G using Equation 3 in which Equations 1 and 2 have beencombined.

As described above, since the ultrasound image processor 110 acquiresthe 3D ultrasound images at thousands of frames per second, and thedisplacement measuring unit 120 measures the displacement of the shearwave having the 3D displacement components, the elastography analyzingunit 130 may calculate the shear modulus G by considering all of the 3Ddisplacement components. That is, the shear modulus G calculated by theelastography analyzing unit 130 has a more accurate value than when itis calculated by two-dimensionally measuring the displacement.

Thus, a shear modulus may be more correctly analyzed when the shearmodulus is analyzed based on 3D ultrasound images acquired by theultrasound probe 20 having a 2D transducer array according to thecurrent embodiment than when the shear modulus is analyzed based on 2Dultrasound images acquired by an ultrasound probe having a 1D transducerarray.

FIG. 4A is an image showing a simulation result of a case where a shearmodulus is analyzed from 2D ultrasound images acquired using an existingultrasound probe having a 1D transducer array. Referring to FIG. 4A, adisplacement map showing a 2D displacement of a shear wave and acorresponding shear modulus map are shown.

FIG. 4B is an image showing a simulation result of a case where a shearmodulus is analyzed from 3D ultrasound images acquired using anultrasound probe having a 2D transducer array according to an embodimentof the present disclosure. Referring to FIG. 4B, a displacement mapshowing a 3D displacement of a shear wave and a corresponding shearmodulus map are shown.

Comparing them with each other, when 2D ultrasound images are acquiredusing the ultrasound probe having a 1D transducer array according toFIG. 4A, since a displacement of the shear wave may not be consideredalong all directions in a 3D space, the shear modulus may not becorrectly analyzed.

However, when 3D ultrasound images are acquired using the ultrasoundprobe having a 2D transducer array according to the current embodiment,since a displacement of the shear wave may be considered along alldirections (x-, y-, and z-axes) in a 3D space, the shear modulus may bemore correctly analyzed than in the case of FIG. 4A.

Referring back to FIG. 1, the elastography analyzing unit 130 provideselastography information based on the calculated shear modulus. Althoughnot shown in FIG. 1, the elastography information, such as the shearmodulus analyzed by the elastography analyzing unit 130, may be providedto a user, such as a medical practitioner, through a display device (notshown) and may be used to perceive a state or a characteristic change intissue.

FIG. 5 is a flowchart illustrating a method of analyzing elastography oftissue using ultrasound waves, according to an embodiment of the presentdisclosure. Referring to FIG. 5, the method includes operationssequentially processed by the apparatus 1 shown in FIG. 1, although theoperations may alternatively be performed by apparatuses or systemsother than apparatus 1. Thus, although omitted below, the descriptionsof the apparatus 1 above also apply to the method according to thecurrent embodiment.

In operation 501, the ultrasound probe 20 may irradiate ROI 30 withultrasound waves using a 2D transducer array, thereby inducing a shearwave in ROI 30.

In operation 502, the ultrasound image processor 110 may acquire 3Dultrasound images with respect to the ROI 30 using echo ultrasoundwaves, which are echos of the ultrasound waves that are received by theultrasound probe 20.

In operation 503, the displacement measuring unit 120 may measure adisplacement of the shear wave in the ROI 30 from the acquiredultrasound images.

In operation 504, the elastography analyzing unit 130 may analyzeelastography information of tissue in the ROI 30 using the measureddisplacement of the shear wave.

As described above, according to the one or more of the aboveembodiments of the present disclosure, since three-dimensionalultrasound images with respect to an ROI are obtained at a relativelyhigh speed, a displacement of a shear wave induced in tissue in thehuman body may be correctly measured. In addition, since thedisplacement of the shear wave is three-dimensionally measured using thethree-dimensional ultrasound images, a shear modulus of the tissue inthe human body may be accurately calculated and provided. Further,decision-making by a medical practitioner in diagnosis or treatment of adisease of a patient may be aided using analyzed information aboutelastography.

The embodiments of the present disclosure can be written as computerprograms and can be implemented in general-use digital computers thatexecute the programs using a computer-readable recording medium. Inaddition, a structure of data used in the embodiments of the presentdisclosure may be recorded on a computer-readable recording medium usingvarious means. Examples of the computer-readable recording mediuminclude storage media, such as magnetic storage media (e.g., ROM, floppydisks, hard disks, etc.) and optical recording media (e.g., CD-ROMs, orDVDs).

In addition, other embodiments of the present disclosure can also beimplemented through computer-readable code/instructions in/on a medium,e.g., a computer-readable recording medium, to control at least oneprocessing element to implement any above described embodiment. Thecomputer-readable recording medium can correspond to any medium/mediapermitting the storage and/or transmission of the computer-readablecode.

The computer-readable code can be recorded/transferred on a medium in avariety of ways, with examples of the computer-readable recording mediumincluding recording media, such as magnetic storage media (e.g., ROM,floppy disks, hard disks, etc.) and optical recording media (e.g.,CD-ROMs, or DVDs), and transmission media such as Internet transmissionmedia. Thus, the medium may be such a defined and measurable structureincluding or carrying a signal or information, such as a device carryinga bitstream according to one or more embodiments of the presentdisclosure. The media may also be a distributed network, so that thecomputer-readable code is stored/transferred and executed in adistributed fashion. Furthermore, the processing element could include aprocessor or a computer processor, and processing elements may bedistributed and/or included in a single device.

The described hardware devices may be configured to act as one or moresoftware modules in order to perform the operations of theabove-described embodiments, or vice versa. Any one or more of thesoftware modules described herein may be executed by a controller suchas a dedicated processor unique to that unit or by a processor common toone or more of the modules. The described methods may be executed on ageneral purpose computer or processor or may be executed on a particularmachine such as the various systems and apparatusses described herein.

It should be understood that the exemplary embodiments described thereinshould be considered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each embodimentshould typically be considered as available for other similar featuresor aspects in other embodiments.

What is claimed is:
 1. A method comprising: inducing a shear wave in atissue in a human body by Acoustic Radiation Force Impulse (ARFI) usingan ultrasound probe having a two-dimensional (2D) transducer array;irradiating ultrasound waves in the tissue using the ultrasound probe;acquiring three-dimensional (3D) ultrasound data using echo ultrasoundwaves of the irradiated ultrasound waves and a 3D plane scan method inwhich a 3D volume of the tissue is scanned by the 2D transducer array;calculating displacement components of the induced shear wave in thetissue based on the acquired 3D ultrasound data; calculating a speed ofthe induced shear wave using the calculated displacement components;calculating a shear modulus of the tissue using the calculated speed ofthe induced shear wave; and displaying at least one 3D image using thecalculated speed of the induced shear wave.
 2. The method of claim 1,wherein the calculating the displacement components of the induced shearwave in the tissue comprises using a wave equation with respect to theinduced shear wave.
 3. The method of claim 1, wherein the irradiatingwith the ultrasound waves is performed for diagnosis of the tissue andcomprises beamforming the ultrasound waves in a defocusing method. 4.The method of claim 1, wherein the acquiring of the 3D ultrasound datacomprises beamforming the echo ultrasound waves.
 5. The method of claim1, further comprising displaying at least one image representing thecalculated displacement components of the induced shear wave.
 6. Themethod of claim 1, further comprising displaying a modulus of elasticitybased on the calculated speed of the induced shear wave.
 7. The methodof claim 1, wherein the speed of the shear wave is calculated using thefollowing equation:$\frac{\partial^{2}u}{\partial t^{2}} = {C_{s}^{2}\left( {\frac{\partial^{2}u}{\partial x^{2}} + \frac{\partial^{2}u}{\partial y^{2}} + \frac{\partial^{2}u}{\partial z^{2}}} \right)}$where u denotes a displacement of the shear wave, t denotes time, and x,y, and z denote the respective calculated displacement components. 8.The method of claim 7, wherein the shear modulus of the tissue iscalculated using the following equation:G=p×C _(S) ² where G denotes the shear modulus of the tissue, and pdenotes a density of the tissue.
 9. A non-transitory computer-readablerecording medium storing a computer-readable program for executing amethod comprising: inducing a shear wave in a tissue in a human body byAcoustic Radiation Force Impulse (ARFI) using an ultrasound probe havinga two-dimensional (2D) transducer array; irradiating ultrasound waves inthe tissue using the ultrasound probe; acquiring three-dimensional (3D)ultrasound data using echo ultrasound waves of the irradiated ultrasoundwaves and a 3D plane scan method in which a 3D volume of the tissue isscanned by the 2D transducer array; calculating displacement componentsof the induced shear wave in the tissue based on the acquired 3Dultrasound data; calculating a speed of the induced shear wave using thecalculated displacement components; calculating a shear modulus of thetissue using the calculated speed of the induced shear wave; anddisplaying at least one 3D image using the calculated speed of theinduced shear wave.
 10. An apparatus comprising: an ultrasound probehaving a two-dimensional (2D) transducer array; a display; at least onehardware processor; computer readable memory comprising instructionsthat, when executed by the at least one hardware processor, performoperations comprising: controlling the ultrasound probe to induce ashear wave in a tissue in a human body by Acoustic Radiation ForceImpulse (ARFI); controlling the ultrasound probe to irradiate ultrasoundwaves in the tissue; acquiring three-dimensional (3D) ultrasound datausing echo ultrasound waves of the irradiated ultrasound waves and a 3Dplane scan method in which a 3D volume of the tissue is scanned by the2D transducer array; calculating displacement components of the inducedshear wave in the tissue based on the acquired 3D ultrasound data;calculating a speed of the induced shear wave using the calculateddisplacement components; calculating a shear modulus of the tissue usingthe calculated speed of the induced shear wave; and displaying at leastone 3D image using the calculated speed of the induced shear wave on thedisplay.
 11. The apparatus of claim 10, wherein the controlling theultrasound probe to irradiate the ultrasound waves comprises irradiatingplane waves by beamforming the ultrasound waves in a defocusing methodand wherein the irradiating of the ultrasound waves is performed fordiagnosis of the tissue.
 12. The apparatus of claim 10, wherein theacquiring of the 3D ultrasound data comprises beamforming the echoultrasound waves.
 13. The apparatus of claim 10, wherein the operationsfurther comprise: acquiring elastography information of the tissue bycalculating an average value of the calculated shear modulus in at leasttwo image frames; and displaying, on the display, at least one imageusing the acquired elastography information.